Many reciprocating internal combustion small engines utilize a governor system to regulate the relationship between carburetor position and engine speed to maintain a constant speed at varying loads. These systems are usually comprised of an internal governor located inside the engine block, a governor shaft that interacts with the internal governor and extends outside the engine block, a governor arm attached to the governor shaft, a linkage between the governor arm and the carburetor valve and a governor spring attached to the governor arm and control plate. When properly assembled, the system balances the forces exerted by the internal governor on the governor shaft with the forces exerted by the spring on the governor arm to achieve the proper relationship between carburetor position and engine speed.
Two major requirements arise with a system of this type. First, the governor arm must be capable of infinite adjustability relative to the governor shaft. Otherwise, the accumulation of design tolerances in the system components could affect the alignment of the governor arm relative to governor shaft position. Each one degree angle change in governor arm position can cause a significant change in the power of the engine. Therefore, all design tolerances must be zeroed out during the assembly of the governor system.
Second, the position of the governor arm relative to the governor shaft must remain fixed during the operation of the engine. During engine operation, the internal governor exerts forces on the governor shaft in a direction opposite to the forces exerted by the governor spring on the governor arm. Therefore, the joint between the governor arm and governor shaft must be capable of carrying the torque created by these opposing forces.
The current governor arm/governor shaft joint used throughout the small engine industry is shown in FIG. 1. The governor arm 13 is made of sheet metal and has two legs, one for connecting a governor spring and one for connecting a linkage to the carburetor. At the intersection of the two legs, the sheet metal governor arm is bent 180.degree. to create a sleeve for the insertion of a bolt. An aperture arranged and configured to allow the insertion of the governor shaft 12 is located near the intersection of the two legs. A "V-shaped" notch is then cut from the bent portion to the aperture, enabling the bent portion to be compressed and the aperture to become smaller. A plate and washer having apertures for inserting a bolt are placed on the top and bottom of the bent portion and the bolt is inserted. A nut is tightened on the bolt compressing the bent portion and reducing the size of the aperture, securing the governor arm to the governor shaft.
The current governor arm/governor shaft joint does provide the infinite adjustability that is required when assembling the governor system, however, it requires three hands to complete the assembly. One hand must hold the governor shaft position, while two more hands are needed to secure the bolt/nut assembly. In addition, because the joint's torque carrying capacity is limited by the ability of the sheared metal edges of the sheet metal governor arm to grip the governor shaft, the existing design has limited torque carrying capacity which can limit governor design parameters.
Therefore, there arises a need for governor arm/governor shaft joint with increased torque carrying capacity and infinite adjustability that will simplify the assembly of the governor system and the zeroing of design tolerances.